1. Field of the Invention
The present invention relates to an image recorder for directing a laser beam onto a recording material to record information about an image on the recording material.
2. Description of the Background Art
An example of background art image recorders directs a laser beam modulated in accordance with an image signal onto a recording material to selectively form a plurality of dots (or a latent image of dots) on the recording medium, thereby recording information about a two-dimensional image thereon. After development, a region on the recording material in which energy exceeding a predetermined threshold is stored is blackened to become a visible dot. For high-quality image recording, it is necessary to record information about an image so that a plurality of dots to be formed have a desired size. Factors which influence the size of dots to be formed on the recording material are roughly divided into three types: factors inherent in a characteristic of the recording material (such as a gamma characteristic of the recording material); factors dependent upon the image recorder (such as the time duration of light emission from a laser light source per dot, and an energy amount (density) of a laser beam or the amount of light emitted from the laser light source); and factors dependent upon a recording material developing apparatus (such as a developer (developing solution) sensitivity, a developer temperature, and developing time).
The influence of the sensitivity of a recording material upon a dot density and a dot size will be described with reference to FIG. 15. FIG. 15 shows a correlation between the amount of energy provided to the recording material by the laser beam and a black density of the recording material. As illustrated in FIG. 15, producing an image at a desired density D on a recording material having a gamma characteristic G0 requires irradiation of the recording material with a laser beam having an energy amount E0, whereas producing an image at a desired density D on a recording material having a gamma characteristic G1 requires irradiation of the recording material with a laser beam having an energy amount E1. Thus, there are variations in required energy amount depending on the sensitivity of the recording material. Further, the energy amount of a beam spot, in general, shows a concentric intensity distribution. Thus, irradiation of the recording material with the laser beam having an energy amount held at E0 in spite of a change in the gamma characteristic of the recording material from G0 to G1 results in the recorded dots having a relatively small size.
Of the three factors (the developer temperature, the developing time and the developer sensitivity) dependent upon the recording material developing apparatus, the developer temperature and the developing time are relatively easily controlled optimally by the developing apparatus. It has been, however, difficult to control the developer sensitivity to be held constant because of its characteristic. This presents a problem such that, even if the image recorder forms a correct latent image of dots on the recording material, the developing apparatus cannot correctly develop the recording material to fail to form dots of desired density and size on the recording material.
The present invention is intended for an image recorder for recording information about a two-dimensional image made up of a plurality of dots on a recording material by relatively moving a laser spot in a main scanning direction and in a sub-scanning direction, the laser spot being formed on the recording material by irradiation with a laser beam.
According to the present invention, the image recorder comprises: a laser light source for emitting the laser beam; a laser light source drive part for driving the laser light source, based on an image signal; an input part for inputting factor information influencing the size of the dots; and a setting part for adjusting and setting a light emission duration per dot and a light emission amount of the laser light source in accordance with the factor information inputted by the input part.
The image recorder can adjust and set the light emission duration per dot and the light emission amount of the laser light source to individually adjust the dimensions, in the main scanning direction and in the sub-scanning direction, of the dots to be formed on the recording material. This allows the proper recording of the information about the two-dimensional image even if a change occurs in the factor information influencing the dot dimensions to cause non-uniform changes in the dot dimensions in the main scanning direction and the sub-scanning direction.
According to one aspect of the present invention, the factor information includes at least one of a first factor related to a characteristic of the recording material and a second factor related to processing of a recorded material.
This allows the proper recording of the information about the two-dimensional image even if a change occurs in at least one of the first factor related to the characteristic of the recording material and the second factor related to processing of the recorded material to cause a change in the dot dimensions.
According to another aspect of the present invention, the image recorder further comprises an image signal correction part for correcting the image signal to be provided to the laser light source drive part, wherein the setting part is capable of providing a light emission timing correction signal for correcting the light emission duration of the laser light source to the image signal correction part, and of providing a light amount setting signal for setting the light emission amount of the laser light source to the laser light source drive part.
This simplifies the adjustment of the light emission duration and the light emission amount of the laser light source.
According to another aspect of the present invention, the image recorder further comprises a memory for storing therein the factor information, the light emission timing correction signal and the light amount setting signal in corresponding relation to each other, wherein the setting part reads from the memory the light emission timing correction signal and the light amount setting signal corresponding to the factor information inputted by the input part.
This facilitates the obtainment of the proper light emission duration and light emission amount of the laser light source corresponding to the factor information.
The present invention is also intended for a method of recording information about a two-dimensional image made up of a plurality of dots on a recording material by relatively moving a laser spot in a main scanning direction and in a sub-scanning direction, the laser spot being formed on the recording material by irradiation with a laser beam.
It is therefore an object of the present invention to provide an image recorder capable of constantly recording information about a desired two-dimensional image on a recording material independently of a change in factor information influencing the size of dots.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.